When building 3 of the Fukushima Daiichi plant exploded last month, those who saw the video footage were left to wonder why it was more severe than the other explosions. Adding to the mystery were reports that the containment and reactor in building 3 were still intact. Gundersen discusses several known facts about Fukushima 3 and theorizes on a possible scenario leading to the explosion.

Transcript:

[tabgroup][tab title="English"]

Good evening. I'm Arnie Gundersen from Fairewinds.

We have been getting a lot of emails at Fairewinds on many topics. But one topic has generated a lot of questions and concerns and some really thoughtful remarks. And that is:

What happened at Unit 3? Why did that explode the way it did compared to Unit 1 and all the other reactors on site. Today, I want to use the opportunity to talk about what we know for sure about Unit 3 and a couple of theories about what could have caused the devastation we see at Unit 3.

To begin with, the Unit 3 explosion is much more dramatic than the Unit 1 explosion. Now engineers have a term called “detonation.” And they have a separate term called “deflagration.” What that means is that they are both explosions in lay terms, but a deflagration, is when the shock wave travels at the speed of sound. A detonation is when the shock wave travels faster than the speed of sound. And a detonation is much more damaging than a deflagration. So that may seem like a technical nuance, but it is really the difference between what happened on Unit 1 and what happened on Unit 3.

If you look at the plume that was generated at Unit 1, it kind of moves away from the building at a much more leisurely pace than what happened at Unit 3.

I would like to go into a couple of things we know for sure about Unit 3 and then postulate the reason why I believe it happened.

First off, it is obviously a much more massive explosion than Unit 1. The second thing is that there is a large amount of energy that goes straight up and we would call that a vector. There is an upward vector on Unit 3 that Unit 1 does not have and that is an important clue here that we will get to in a minute.

The next thing is that it is clear in Unit 3 that there is an explosion. If you look at the south side of the building, that is the right side of the building, there is a bright yellow flash before the black smoke begins to go upward. That is another important clue that we will get to in a minute. The other thing is that pieces of nuclear fuel rods were discovered as far away as two miles from the plant. If you look at Unit 4, which we have talked about in the past, the fuel rods are dry but the fuel racks are intact. So it is really unlikely that nuclear fuel rods could be thrown from the Unit 4 pool a couple miles away, which leads us to the fact that the fuel that has been found off site had to come from Unit 3.

The other things that have been discovered is that uranium, as a very fine dust, has been found in Hawaii and on the West Coast. Plutonium has been found on the site as a very fine, powdery dust. And another element, called americium, has been found in New England. All of those are what we call transuranics, they are heavier than uranium. And that is an indication that nuclear fuel was damaged and that nuclear fuel was volatilized at Fukushima. The other things are that the photographs of Unit 3 after the explosion indicated that a large portion of the building is missing, especially on the south side. But yet the infrared picture of the same building, shows a heat source still on the south side.

Last, but not least, is that we are sure, that the data indicates that the containment itself and the reactor itself on Unit 3 remain intact.

So we have got a mystery here. We have got a reactor and a containment intact but we knew the building was blown to smithereens. Why? I believe that the fuel pool, which is a large 50 by 50 by 50 feet deep container, was empty and it filled with gasses and blew upward. Now the top of that pool would be open, the sides would be a barrier, and that could be the cause of that upward projection of material. Now that accounts for a couple more things. Basically what I am saying is that the fuel pool is like a muzzle of a gun. It was pointing upward and it blew upward. And the other thing is that if you look at the photos, there was an awful lot of rubble coming back down. Now that is fuel racks, fuel rods, and pieces of uranium and plutonium.

So that accounts for the fact that uranium and plutonium were found as far away as a couple of miles off site. The other thing it shows is that the blackness of that cloud indicates that uranium and plutonium were volatilized. In other words, they were turned into a really fine aerosol which can find it's way across the Pacific and in Hawaii and on the West Coast and now here in New England as well.

So here is the question: what caused that upward force? If it were just hydrogen, a hydrogen-oxygen reaction would create water. When that happens, the sound wave travels at the speed of sound and it is a deflagration. That is what happened in Unit 1. It is dramatic, but it is not explosive.

What caused the explosion in Unit 3? Clearly, there was an explosion for two reasons. One is the magnitude of the plume moving upward and the other reason is the red flash on the side of the building. A deflagration does not give a red flash like that, a detonation does. So the question is what caused the detonation? A hydrogen-oxygen reaction alone will not do it. There has to be something more here.

The jury is still out on why. But a plausible reason is that the hydrogen reaction started, which then caused a shock wave to move and distort the nuclear fuel in the pool. The distortion of the nuclear fuel in the pool, creates a prompt nuclear reaction, which then blows the rubble out of the pool, up in the plume and creates the energy needed to create the dramatic event that we have seen at Fukushima Unit 3.

There is a way to test this hypothesis and the way to test it is to look at the types of isotopes that are in that smoke. Now we know the military had planes up and we can also assume that there were laboratories counting the material. There are two xenon isotopes and depending on the ratio, we can determine if it was a prompt criticality or not in that fuel pool.

So the evidence is there, but we are not getting it yet, but I would assume that our government has it. Well thank you very much and as more information becomes available, I will keep you informed.

At least $8.2 Trillion would be needed to build the 1,000 atomic reactors the nuclear industry wants – that’s 1 reactor every 12-days for 35-years. Watch Fairewind's animation to see what it means and why!

Smokescreen

It is time to protect the air we breathe, the food we eat, and the water we drink. Don't deny science!